In the above scenario, the Protocol column in the Outlook Connection Status dialog shows Outlook 2013 is connected to the Exchange server using a connection mechanism other than MAPI/HTTP. For example, the following figure shows a connection using RPC/HTTP.

Note MAPI/HTTP connections are designated in the Protocol column using the string HTTP.

Cause

This problem can occur if the MapiHttp feature is disabled on the Outlook client using the following registry value: